My reconstruction of the instrument is mainly based on my own interpretation of its possible musical function. Since I want to consider iit as a genuine polyphonic instrument I invented a special keyboard, fit for 12th century two voices polyphonies, suggesting also a diffferent managing of the wheel.

Keyboard

By tuning the strings either: A – d – a or: A – e – a we get an overall extension of two chromatic octaves (minus the last semitone). Before lifting each key, the performer can choose which string he is going to touch, simply by turning the key to the proper position: the first one allows him to operate on the bass string, the second on the middle one, the third on the higher string.

Thus it is possible to play two different melodic lines simultaneously. In Santiago sculpture the hands of the musician on the right are on the third and on the fifth key. This means he is playing -c, g - rather than -d, f - bichord on bass and middle strings, or - g, c’ rather than - f, d’- bichord on middle and higher strings (first tuning).

First string a.. a# b c’ c’# d’

Middle string d.. d# e f f# g

Bass string A.. A# B c c# d

Keys 0 1 2 3 4 5

In position 4 the key is provided with two tangents so as to act on second and third strings (tuned either in Fifth or Fourth) at the same time to perform Organum parallelum, leaving the bass string as a drone.

How they calculated the semitones progression

Known medieval texts neither describe nor discuss about the possibility of a chromatic scale. But, reading Boethius's De institutione musica, easy to be found in monastic libraries since 9th century on, the monks could learn a lot about semitones both from pythagorean tradition and from Aristoxen's. There are only few lines, but enough, dedicated to the description of Aristoxen's practical method to divide the monochord. From this source the medieval scholar could learn a practical method in order to draw a correct chromatic scale of 12 tempered semitones. We discuss about this in another blog in this website

connecting astronomical and musical knowledges through 10th and 12th centuries. Anyway, this idea comes from very early roman sources: Plinius and Boethius. In case the author of Santiago instrument intended to describe a revolutionary full chromatic/polyphonic keyboard we can suppose he was aware of that very ancient tradition.

Wheel

On the other side, the musician who is in charge of turning the crank, by a smooth, even movement of his right hand, can also lift one or even two of the strings from the edge of the wheel with his left hand in order to stop them vibrating. This way you can either avoid conflicts between the voices or stop undesired drone effects.

"(the diapason) contains 5 tones and 2 semitones/the fifth and the fourth/is the highest unity of symphoniae, or sounds"

SYMPHONIA matches with the medieval highest idea of music and sound, while ORGANISTRUM sounds like a deformation of the word ORGAN and like a ridiculous nickmame.

I believe that the name Organistrum fits better the later "one-man Lyre", a diatonic, melodic instruments with drones, sort of early hurdygurdy used for secular music.

(Ch.Page is of the same opinion)

BUILDING A REPLICA OF SANTIAGO DE COMPOSTELA INSTRUMENT

I chose one big Red Willow (Salix purpurea) planck, seasoned in nature, from which I carved the sound box and the base of the keyboard in one piece, average thickness 8-10 mm. Flat back, flat sides as in the original.

GENERAL MEASURES:

Total length 940mm

Max width 230mm

Depth 80mm

Diapason 720mm

In the bottom of sound box I drilled a 10mm hole for the wooden axis, made of Beech (Fagus silvestris). Axis ends into another hole of 10mm drilled directly with no axle box in a wooden bar (Spruce) 15mm thick, glued between the two lobes of sound box which has been carved out of one piece of Spruce (Picea abies) 8mm thick with no other bars glued underneath. Keyboard box is independent from the body of the instrument and can be easily removed to modify general level of the bars, changing their angle with the strings or making reparations. The 11 bars of the keys, diameter 10mm, are of Pine (Pinus nigra) and the 55 pivoting tangents of Beech. The problem of the distances among the bars is discussed in the present article. To avoid noise made by the bars returning to their previous position, after being pulled up to play, a stripe of cloth has been glued at the bottom of the keyboard. The carved lid has been made of Spruce, 8mm thick and is simply interlocked with the body of the keyboard without any hinge or other device.

The wheel, 11cm wide and 20mm thick is of Walnut (Juglans regia) and forced on wooden axis without any screw, nail, or wedge. No axle box at the end. The Beech crank , stuck in the square end of the axis, can be easily removed. The soundboard is glued to the body of the instrument , no sound pole in it. The bridge is of Poplar (Populus nigra) reinforced with a Beech edge. The tailpiece of Chestnut (Castanea sativa) is linked to the bottom of sound box by a leather lace. Tuning pegs are of Beech, no need for a tuning key. Two light layers of pure almond oil have been used as finishing . Gut strings: 0.80, 1.10, 1.40mm.

Gate of Glory extrados in Santiago de Compostela Cathedral is crowded by statues bearing different kinds of stringed instruments. At the very top of the gate two of them are playing a beautifully carved and decorated instrument, the so calledOrganistrum.

2 : The top instrument:

This curious object has been largely studied and several reconstructions have been proposed and carried out by scholars and luthiers during the past 40 years, nevertheless some aspects are still uncertain, such as its symbolic significance and its peculiar musical role.

3 :: Symphonia::

Let’s start considering its special location.The statues of the extrados represent the 24 elders of Apocalypse. They can be symbols of Time (24), Music (musical instruments) and Divine symphony (they are heavenly creatures) too.

4 :: Two Performers::

The two performers at the top are very close to Christ’s head, position as usual occupied by angels. If we compare them to the other musicians we observe they look to be the only two actually playing and they are playing the most complex instrument of all. The idea that it could be given a deeper symbolic significance is strengthened by closer observation of its features. A revolving object, the wheel, creates the sound from strings stretched over a sound box made of two equal circles, to which an unusual keyboard is added, equipped with 11 keys, so that the octave is divided into 12 parts.

All this is strange enough and absolutely unique, in XII century atleast !, and we need referring to any kind of theological, philosophical, mathematical and musical theory of the age to give a reasonable interpretation of it. Medieval Latin Platonism, for example, mainly related to Chartres cathedral school, well connected with Paris and Santiago, brings to us interesting suggestions.

5 :: Ordering the Heavens::

Platonists thought that at the beginning of creation, making the World Soul, Demiurgos was dealing with three abstract elements: Being, Sameness and Difference. Establishing the right proportions among sameness and difference, he gave the World Soul the shape of two circles one inside the other and put them into the material World, thus creating both the Sphere of fixed stars and the plane of planetary orbits. Circular motions of planets and stars were thus connected in perfect harmony, like the strings of a well tuned Lyre or the pipes of a well cut Pan flute[1].This set-up is reflected in our instrument.

6 :: Symphonia Coelistis::

A circular sound box, theCircle of Sameness, contains the wheel , that represents planetary motion: the Circle of Difference. This is the origin: the invisible World Soul. Thenanother circle is added, the visible world, Cosmos, with its charming beauty. At lastwe find the keyboard, with 11 keys dividing the octave in parts, the symbol of human mind, which divides and measures in order to understand Natural phenomena. Therefore, the widespread philosophical principle “Veritas est adaequatio intellectus et rei “ (translation: truth is an adjustement between intellect and things) is well represented here, as we can observe that the vibrating string-length (rectilinear thought) is equal to the circumference of each circle of the sound box (Nature and abstract world).

Further suggestions come fromthe analysis of instrument decorations.

A long line of DOTS runs all around the outline of the instrument. They are symbols of the stars. From left to right: first circle, the idea of the stars in the abstract world; second circle, the visible stars; keyboard, our knowledge of the stars (straightened).

The large ROSETTE in the middle represents the Visible World, a circular figure divided in four equal sections by two perpendicular axes. Each section is occupied by a five lobes leaf and twigs (these leaves are similar to those sculpted all around the 24 Elders). The division in four sections may refer to the four elements of material world.

7 :: Diagram of the Seasons

This figure recalls diagrams of the seasons frequently drawn in glosses of IX-XII century astronomical manuscripts or even more elaborated drawings.The main goal of any scholar was to calculate accurately the length of each season in order to obtain an exact and affordable calendar to establish with great accuracy both the dates of Christian feasts and the right hours for prayer in monasteries[2].

8 :: IX-XII centuries decoration patterns ::

Finally, KEYBOARD LID decoration, unique among all other decorations sculpted in the Gate, shows a rare pattern, which had been popular in some areas around the Alps and in Ireland between IX and XI centuries, rather neglected in the XII[3].

9 :: Keyboard ::

Each knot of the interlace corresponds precisely to one key of the 11keys protruding out of the rectangular box. This division in fact is the most puzzling feature of all, as nobody could justify the introduction of a chromatic scale in XII century, when only strict diatonism was allowed. But we discovered that, curiously enough, both the unusual decoration and the division of the octave in 12 semitones can be referred to diagrams of planetary latitudes, related to musical scales as well, in astronomical manuscripts of the age.

10 :: Planetary latitudes diagrams ::

Such diagrams were intended to represent planetary latitudes across the zodiacal band, divided vertically in 12 degrees. As usual the horizontal line of these grids was divided in 30 parts, but since XI century we often find 12 in order to signify the 12 zodiacal signs. The Sun and Saturn were given a serpentine path within the two middle degrees of the zodiac, Jupiter had three degrees, Mars four, Mercury eight, the Moon covered the zodiacal band with its 12 degrees of latitude. Venus was assigned a latitude of 14 degrees, one degree beyond the zodiac on each side.

11 :: Planetary latitudes diagrams ::

Then, in a manuscript by Abbo de Fleury (c 940-1004) we find a horizontal column list of the Plinian intervals between planetary orbits attached to planetary latitudes grid[4]. Whether 14 semitones can be counted in total, the musical octave spanning from Moon to Saturn is divided into 12 semitones (semitone being the unit of measurement of the scale, clearly enough).Thus, our XII century chromatic scale shouldn’t be considered as a scandal any longer! Besides, experimenting with our special keyboard with keys ranging about two full chromatic octaves demonstrates that this arrangement fits quite well XII century two voices polyphonic music.

12 :: The name

For these reasons we feel the name of Symphonia or Symphonia magna or Symphonia caelestis would be more appropriate for this instrument than the usual, uncertain and rather mocking name of Organistrum.

Its representationin Santiago could have been an exclusive message for a restricted group of scholars capable of understanding the cosmological and musical implications of a non-traditional object that had been invented of course by monks trained in the liberal arts of Quadrivium.

The famous Gate of Glory in Santiago de Compostela Cathedral (Galicia), dedicated toSt. James (Unceta, 2004), recently examined in an interesting archaeoastronomical perspective(Vilas Estevéz and Gonzalez-Garcia, 2016) too, has been built following an iconographic projectinspired by St. John’s book of Apocalypse (Moralejo, 1988). At the top of main arch, in the middleof the 24 venerable men’s row around Christ’s throne, there is a peculiar musical instrument (Fig.1) -equipped with a wheel- played by two of them (Luengo, 1988). The particular position, theextremely accurate details and the peculiarity of the instrument underline the importance of anobject whose origins, symbolism and actual musical role (Lopez-Calo, 1988) have never beencompletely explained.The most intriguing features are: a) 12 intervals division of the octave; b) wheel used to producesound; c) general shape and decorations. In this article we introduce a possible interpretation ofOrganistrum as a sampler of cosmological and astronomical knowledge typical of European culturefrom IX to XII century (Eastwood, 1997; McCluskey, 1998). Close relationship between astronomyand music in platonic-pythagorean doctrines (Albertazzi, 2010) is confirmed through detailedanalysis of astronomical texts in manuscripts copied in Benedictine scriptoria from CarolingianRenaissance onwards (Eastwood, 2007).Beyond general reference to Plato’s Timaeus, through Macrobius and Calcidius commentaries(Martello, 2011), main suggestions to our study come from interesting diagrams (Eastwood andGrasshoff, 2004) found in these manuscripts (e.g.: clm 14436, f.61r, Munich BayerischeStaatsbibliothek). Organistrum could be considered a representation of Cosmos, a sort of acousticplanetary, the Christian answer to Oud’s astronomical interpretation proposed by Arabic school(Severini, 2015), that by the ninth century had moved from Baghdad to Cordoba (Godwin, 1993;Lindberg, 1992).